Deriving allowable daily intakes for systemic toxicants lacking chronic toxicity data.

The lack of human toxicological data for most chemical compounds makes it difficult to quickly assess health risks associated with exposure to contaminants at hazardous waste sites. It would therefore be advantageous to have a technique for estimating acceptable daily intakes (ADIs) of potentially toxic substances based on more widely available animal toxicity data. This article focuses on the use of LD50 data to derive provisional ADIs, and it suggests multiplying oral LD50 values (expressed in mg/kg of body wt) by a factor in the range of 5 X 10(-6) to 1 X 10(-5) day-1 to convert them to such ADIs.

Screening the potential risks of toxic substances using a multimedia compartment model: estimation of human exposure.

Managing environmental health risks requires the assessment of environmental fate, exposure, and health risk of an ever-increasing list of contaminants. The magnitude of this list precludes an experimental evaluation of each contaminant. For this reason, computer models are being used more frequently to simulate the transport and transformation of chemicals based on physical and chemical properties.

Myelodysplastic syndromes: their history, evolution and relation to acute myeloid leukaemia.

The myelodysplastic syndromes (MDS) constitute a heterogeneous group of clonal disorders arising from a multipotent haemopoietic progenitor which share a leukaemic propensity, 30% of cases culminating in acute myeloid leukaemia (AML). Their pathogenesis probably entails multiple steps, phenotypic progression being determined by either expansion or evolution of the abnormal clone. The clonal origin of certain cases of de novo AML is analogous to that of MDS and evidence that they share a common pathogenesis and distinct biological characteristics is beginning to emerge.

Preliminary communication--treatment of primary brain tumors recurrent after irradiation with aziridinylbenzoquinone (AZQ;NSC-182986).

Twenty-nine patients with primary brain tumors recurrent or progressive after cerebral irradiation were treated with AZQ. Twenty of the 29 patients had also failed prior chemotherapy. CT scan-documented tumor regressions were noted in 17.

Liposomally activated macrophages; subsequent interaction with L1210 leukemic cells.

The coincubation of liposomes with mouse leukemia cells or fibroblasts can cause a wide of effects on their viability. These effects are not particular specific in terms of destroying the leukemic cells. However, it was observed that the combination of phosphorylcholine-cholesterol (PC-CHOL)1-liposomes, which are not toxic by themselves, with alkyl-lysophospholipids as components of the liposome, can produce the desired specific cytotoxicity for leukemic cells.

Phase II studies of dianhydrogalactitol-based combination chemotherapy for recurrent brain tumors.

The drug combinations of dianhydrogalactitol and VP-16 and dianhydrogalactitol, VP-16, and triazinate were used in patients with primary brain tumors, principally astrocytoma, recurrent following cranial irradiation. Tumor regressions were noted in 40% of patients treated with the 2-drug regimen and in 33% of patients treated with the 3-drug regimens. Regression were noted in all grades of tumor.

Dianhydrogalactitol and radiation therapy. Treatment of supratentorial glioma.

Dianhydrogalactitol was the most active of 177 agents tested against a mouse ependymoblastoma tumor. We conducted a prospectively randomized trial comparing whole-brain irradiation alone vs identical irradiation plus dianhydrogalactitol in 42 patients with grade 3 and 4 supratentorial astrocytomas. Patients receiving dianhydrogalactitol in addition to irradiation had a significantly longer median survival time (67 vs 35 weeks) than did patients receiving only irradiation.

An analysis of the binding of fluorescence probes in mitochondrial systems.

Measurements of the binding of the fluorescent probes 8-anilinonaphthalene-1-sulfonate (ANS) and ethidium ions to whole and disruped mitochondria and submitochondrial particles suggest that the inner mitochondrial membrane is freely permeable to the two probes. Equations relating the binding of permeant probes to the electro-chemical balance across the membrane of vesicular systems are derived and these equations used to analyze Scatchard plots of the binding of the two probes to energized and nonenergized mitochondria and EDTA particles.

The diagnosis and natural history of spinal cord arteriovenous malformations.

The present study of 71 patients shows that the initial symptoms often cannot differentiate spinal cord arteriovenous malformation from other lesions causing cord dysfunction, but the picture at the time of presentation may suggest the diagnosis. Most patients are males with neurologic findings referable to the thoracolumbar area who present with gradually progressive pain, weadness, sensory distubance, and disturbance of micturition. Early impairment of micturition may help suggest this lesion because it is less likely to be an early complaint in patients with disk disease or tumor affecting the spinal cord.

Controlled study of CCNU and radiation therapy in malignant astrocytoma.

The authors report 63 patients with biopsy-proved malignant (Grades 3 and 4) astrocytomas who were randomly placed in one of three treatment schedules within 2 weeks of surgery. One group (22 patients) received radiation therapy alone; the second group (22 patients) received 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) orally at intervals of 8 weeks; and the third group (19 patients) received combined radiation and drug therapy. Patients who received radiation therapy, with or without the drug, had a significantly longer survival than did those who received the drug alone.

An unusual compressive syndrome of the cauda equina.

An unusual case of a capillary hemangioma of the filum terminale is presented. The successful removal returned the patient to an asymptomatic state.